Advanced Multi-Purpose Multistage Evaporative Cold Water/Cold Air Generating and Supply System

ABSTRACT

This discloses apparatuses for industrial or commercial cooling (or any other cooling) using staged cooling towers to evaporatively reach temperatures below the wet bulb temperature of the ambient air. Methods for using such apparatuses are disclosed as well.

BACKGROUND

This document introduces a new method and system for a sustainable . . .high-performance . . . low-energy consumption combination of direct andindirect evaporative cooling processes providing maximum cooling atmaximum energy efficiency called the Multistage Evaporative CoolingSystem (MECS). The method and system of the MECS uses awater-into-ambient-air evaporation process.

Water evaporation processes for a variety of comfort and process-coolingneeds have existed for many centuries. The most current representativeapplications of evaporative cooling are the home evaporative air coolers(swamp coolers) and commercial and industrial cooling towers. Thecooling apparatuses are relatively simple in design and operation, andthey evaporate water directly into ambient air from different types ofwet media, which usually have large surface areas. Physics limits thetemperature that these cooling apparatuses can achieve when cooling airor water. The wet bulb temperature of the ambient air and the coolingsystem's design primarily govern the cooling apparatus's low-temperaturelimit. But regardless of the design of these single stage evaporativecooling apparatuses, the wet bulb temperature of the ambient air is thetheoretical absolute low limit for the achievable final temperature ofthe cooled media (air or water). In other words, under no circumstancescan the final temperature of the cooled media for the above apparatusesachieve a value equal to or lower than the ambient air's wet bulbtemperature: there will always be some difference between the wet bulbtemperature of the ambient air and cold air or water from the apparatus.This temperature difference is defined as an “approach temperature”. Theapproach temperature value varies greatly depending on the coolingapparatus's design. The temperature of the cold air or cold water fromthe adiabatic cooling apparatus will always be higher than the wet bulbtemperature of the entering air being cooled by the apparatus. In otherwords, the approach temperature of the adiabatic cooling apparatusequals the temperature of the cold water produced by the apparatus minusthe wet bulb temperature of the entering air. For general applicationsof these cooling apparatus, the approach temperature is within a rangeof 5 to 10° F.

The design of invention embodiments arises from applying engineeringprincipals to discover component arrangements and sequencing ofcomponents that result in the ambient air wet bulb temperature barrierbeing lowered.

Another way of stating the above is as follows. In traditionalsingle-stage direct evaporative cooling, the evaporative cooling processlowers the dry bulb temperature of the processed air (ambient air or amixture of ambient air and return air), while the wet bulb temperatureand enthalpy of the processed air are not changed—they are equal totheir initial values. In the single-stage direct evaporative coolingprocess, the initial wet bulb temperature of the adiabatically processedair is the absolute theoretical temperature limit for the dry bulbtemperature of the adiabatically cooled processed air. As stated above,the difference between the dry bulb temperature of the adiabaticallycooled air and its wet bulb temperature is known as the “approachtemperature”.

This principal establishes the following: the lower the approachtemperature the higher the efficiency of the adiabatic cooling process.The single stage direct evaporative cooling system/unit is not capableof achieving required temperature levels of cooling media (air or water)that is appropriate for practical use in a majority of demanding coolingapplications.

Therefore, there is a strong need for the creation of new universalmethods and systems allowing maximum utilization of the laws ofthermodynamics related to evaporative cooling applications providingeffective and energy efficient evaporative cooling systems for a widevariety of applications by using methods incorporating multiple stagesof evaporative cooling.

SUMMARY

The Inventor has developed new methods and systems that provideevaporative cooling by combining multiple direct and indirectevaporative cooling stages into one multistage evaporative coolingsystem to achieve cooling media (air or water) temperatures that aremuch lower than the initial wet bulb temperature of the ambient air. TheInventor has named this cooling system the Multistage EvaporativeCooling System (MECS: sometimes referred to simply as a cooling system).This new approach and method of the combined multiple direct andindirect evaporative cooling processes fully complies with all laws ofthermodynamics by properly sequencing components and actions to achievemaximum cooling at a minimal energy use. The MECS outperformsconventional refrigeration systems by using at least 50% less energy tooperate. The MECS's resulting output is cold air, cold water, or both.For some critical cooling applications (for instance, cooling of largevolumes of makeup air) at low or moderate ambient air humidity levels,MECS significantly outperforms comparable Conventional MechanicalRefrigeration Systems.

Invention embodiments are drawn to cooling systems with at least twostages. The first-stage cooling assembly includes a forced-draft coolingtower with an air inlet, an air outlet, a cold water reservoir, avariable speed fan, and a variable flow water pump that is adapted topump cold water through first-stage supply piping. The final-stagecooling assembly includes a forced-draft cooling tower with an airinlet, an air outlet, a cold water reservoir, a variable speed fan, anair-to-water heat exchanger at the air inlet of the final-stage coolingtower and a variable flow water pump that is adapted to pump cold waterthrough final-stage supply piping. This assembly is connected so thatcold water produced from operating the first stage can be pumped to aheat exchanger on the final stage (or in some embodiments, anotherstage) and/or some other cooling load. The heat exchanger cools ambientair as it enters the final stage cooling tower. Ultimately, since thefinal stage cooling tower operates with air that is colder than theambient air used by the cooling tower in the first stage, the finalstage cooling tower can produce water that is colder than the wet bulbtemperature of the ambient air. Various embodiments comprise command andcontrol systems to operate the mechanical components of the coolingsystem to avoid operating at over capacity or any other operating regimethat wastes energy.

Some embodiments include one or more additionally intermediate-stagecooling assemblies that comprises a forced-draft cooling tower with anair inlet, an air outlet, a cold water reservoir, a variable speed fan,an air-to-water heat exchanger at the air inlet of theintermediate-stage cooling tower and a variable flow water pump that isadapted to pump cold water through intermediate-stage supply piping.

Operation of three or more stages has cold water from the first stagecooling air entering an intermediate stage with the final stageair-to-water heat exchangers being fed from one or more intermediatestages allowing even lower cold water temperatures to be reached.

In some embodiments, any of the cooling towers may direct all or some oftheir cold exhaust air exiting the cooling tower through an energyrecovery system that uses an air-to-water heat exchanger and the coldair to create a cold water supply for additional cooling wherever suchcooling is needed. The energy recover system is typically operated as aclosed loop system.

In some embodiments, the final stage is used to cool various coolingloads such as process cooling loads or cools the make up air flowingthrough the make up air handling unit for supplying cold air to thebuilding.

Some method embodiments include steps of supplying the cooling stagesdescribed above and operating the cooling stages so that the finalcooling stage or one or more of the intermediate cooling stages producecold water with a temperature below the ambient wet bulb temperature ofthe air used in the cooling process.

In some embodiments, the energy recovery system includes an air inletadapted to receive cool air from a cool air source, an air-to-water heatexchanger, a fan, a pump, piping connecting from the air-to-water heatexchanger to a cooling load then to the pump and then back to theair-to-water heat exchanger or from the air-to-water heat exchanger tothe pump and then to a cooling load and then back to the air-to-waterheat exchanger. The energy recovery system uses waste cool air exhaustfrom a cooling tower in some embodiments.

FIGURES

FIG. 1 depicts a cooling tower useful in invention cooling systemembodiments.

FIG. 2 depicts another useful cooling tower further comprising anair-to-water heat exhanger or an air pre-cooling heat exchanger.

FIG. 3 depicts another useful cooling tower further comprising an energyrecovery system.

FIG. 4 depicts a cooling system embodiment of the invention.

FIG. 5 depicts another cooling system embodiment of the invention.

FIG. 6 depicts another cooling system embodiment of the invention.

FIG. 7 depicts a makeup air handling unit.

FIG. 8 depicts an energy recovery system, such as seen in FIG. 3.

DETAILED DESCRIPTION

The following description of several embodiments describes non-limitingexamples that further illustrate the invention. No titles of sectionscontained herein, including those appearing above, are limitations onthe invention, but rather they are provided to structure theillustrative description of the invention that is provided by thespecification.

Unless defined otherwise, all technical and scientific terms used inthis document have the same meanings that one skilled in the art towhich the disclosed invention pertains would ascribe to them. Thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly indicates otherwise. Thus, for example, reference to“fluid” refers to one or more fluids, such as two or more fluids, threeor more fluids, etc. Any mention of an element includes that element'sequivalents as known to those skilled in the art.

Any methods and materials similar or equivalent to those described inthis document can be used in the practice or testing of the presentinvention. This disclosure incorporates by reference all publicationsmentioned in this disclosure and all of the information disclosed in thepublications.

This disclosure discusses publications only to facilitate describing thecurrent invention. Their inclusion in this document is not an admissionthat they are effective prior art to this invention, nor does itindicate that their dates of publication or effectiveness are as printedon the document.

The features, aspects, and advantages of the invention will become moreapparent from the following detailed description, appended claims, andaccompanying drawings.

Exemplary Features of the MECS

The MECS's new methods and systems allows the generation of supply airor cooling fluid, such as water, at a low temperature, meeting theconditioned space's temperature control requirements without addingmoisture to the supply air or fluid in most cases.

-   -   Design Simplicity (MECS does not need to rely on any        high-energy-using refrigeration compressors).    -   Ecologically sound design (MECS uses only water and atmospheric        air—no need to use Freon-type refrigerants such as        hydrochlorofluorocarbons (HCFCs)).    -   Scalability (MECS can be scaled to provide as little as 5 tons        to well over 500 tons of equivalent Conventional Mechanical        Refrigeration Cooling).    -   Economical Energy Use (MECS has significantly lower power        consumption compared to Conventional Mechanical Refrigeration        Systems).    -   Green Electrical Energy Use (MECS can use green electrical        energy sources (solar, wind, etc.).

FIG. 1 shows cooling tower 10, a Type-I cooling tower. Cooling tower 10comprises tower casing 15, cold-water reservoir 20, air inlet 35, airoutlet 40, water distribution system with nozzles 51, fan 55, pump 60,cold water outlet 65, warm water inlet 66, and mist eliminator 71. Fan55 is not present in some embodiments. Air inlet 35 sits near the bottomof cooling tower 10 in the embodiment depicted by FIG. 1. Otherembodiments can be envisioned in which air inlet 35 sits remotely fromcooling tower 10, but in those embodiments, ambient air should entercooling tower 10 below air outlet 40. Cold-water reservoir 20 sits nearthe bottom of cooling tower 10. But other embodiments exist in whichcold-water reservoir 20 sits remotely from cooling tower 10. In thosetypes of embodiments, one of ordinary skill in the art would recognizethat additional piping and plumbing would be useful in such embodiments.

In some embodiments, airflow through cooling tower 10 is assisted by fan55. Fan 55 sits near the uppermost part of cooling tower 10 near airoutlet 40. Fan 55 may either be located downstream of mist eliminator 71or upstream of mist eliminator 71. Alternatively, a fan may mount at theinlet of cooling tower 10, pushing ambient air through cooling tower 10.Of course, a cooling tower could use two or more fans.

In some embodiments, water is distributed by the water distributionsystem with nozzles 51 over a mass heat transfer media (fill). In thesetypes of embodiments, one of ordinary skill in the art would recognizethat mass heat transfer occurs through the interaction between the waterand air on the surface of the fill.

As stated previously, FIG. 1 depicts fan 55 on the top of cooling tower10. Mist eliminator 71 sits near the top of cooling tower 10 in theembodiment depicted in FIG. 1, as will be the case in most embodimentsthat employ a counter flow design. Some embodiments may use a cross flowcooling tower design, which would lead to a different arrangement of airinlets, water distribution systems, fans, etc. Water distribution systemwith nozzles 51 attaches to warm water inlet 66, which connects betweencooling load 11 at the warm water outlet of air-to-water heat exchanger230 and water distribution system with nozzles 51. Pump 60 connects tocold-water reservoir 20 and connects to cooling loads 11 and an externalair-to-water heat exchanger, such as air-to-water heat exchanger 230,through cold water outlet 65. Cold water outlet 65 also connects to thecold water inlet of air-to-water heat exchanger 230.

Invention cooling systems use a variety of cooling towers in addition tocooling tower 10.

FIG. 2 shows another type of cooling tower used in invention coolingsystems—cooling tower 210, a Type-II cooling tower. Cooling tower 210comprises tower casing 15′, cold-water reservoir 20′, air inlet 35′, airoutlet 40′, water distribution system with nozzles 51′, fan 55′, pump60′, cold water outlet 65′, warm water inlet 66′, mist eliminator 71′,and air-to-water heat exchanger 230.

Air-to-water heat exchanger 230 comprises a housing 231, heat exchangercold water inlet 213, and heat exchanger warm water outlet 214. In someembodiments, heat exchanger cold water inlet 213 connects to cold wateroutlet 65 and heat exchanger warm water outlet 214 connects to warmwater inlet 66 of a Type-I cooling tower. In other embodiments, heatexchanger cold water inlet 213 connects to cold water outlet 65′ andheat exchanger warm water outlet 214 connects to warm water inlet 66′ ofa Type-II cooling tower.

Air inlet 35′ sits near the bottom of cooling tower 210, in theembodiment depicted by FIG. 2. Other embodiments exist in which airinlet 35′ sits remotely from cooling tower 210 as long as ambient airenters cooling tower 210 below air outlet 40′. Air-to-water heatexchanger 230 sits between air inlet 35′ and cooling tower 210.Cold-water reservoir 20′ sits near the bottom of cooling tower 210. Butother embodiments exist in which cold-water reservoir 20′ sits remotelyfrom cooling tower 210. In those types of embodiments, one of ordinaryskill in the art would recognize that additional piping and plumbingwould be useful.

In some embodiments, fan 55′ assists air in flowing through coolingtower 210. Fan 55′ sits on the top of cooling tower 210 near air outlet40′. Fan 55′ may sit either downstream of mist eliminator 71′ orupstream of mist eliminator 71′. Alternatively, a fan mounts at theinlet of cooling tower 210, designed to push ambient air through coolingtower 210. Of course, this cooling tower may use two or more fans.

In some embodiments, water is distributed by the water distributionsystem with nozzles 51 over a mass heat transfer media (fill). In thesetypes of embodiments, one of ordinary skill in the art would recognizethe mass heat transfer interaction between the water and air on thesurface of the fill.

Pump 60′ is in fluid communication with cold-water reservoir 20′ and influid communication with water distribution system with nozzles 51′,which is located near the uppermost part of cooling tower 210. In someembodiments, “fluid communication” encompasses a cold water outlet 65′connected to pump 60′. Cold water outlet 65′ connects through anexternal device, comprising a pipe, heat exchanger, or other externaldevice (such as cooling load 11′), to warm water inlet 66′. In these orother embodiments, pump 60′ connects to cold-water reservoir 20′ andconnects to cooling loads 11′ and an external air-to-water heatexchanger, such as air-to-water heat exchanger 230′, through cold wateroutlet 65′. Warm water inlet 66′ connects to water distribution systemwith nozzles 51′. In some embodiments, cold water outlet 65′ connects toan external device such as an air-to-water heat exchanger mounted uponanother or an adjacent cooling tower or a cooling tower of anothercooling stage, and then continues on to water distribution system withnozzles 51′ through warm water inlet 66′.

In some embodiments, pump 60′ services water distribution system withnozzles 51′. In these or other embodiments, pump 60′ or another pumppumps cold water from cold-water reservoir 20′ to the cold water inleton an air-to-water heat exchanger mounted on another cooling tower andanother pump pumps water to water distribution system with nozzles 51′.

FIG. 3 shows another type of cooling tower for use in invention coolingsystems—Cooling tower 310, a Type-III cooling tower. Cooling tower 310comprises tower casing 15″, cold-water reservoir 20″, air inlet 35″, airoutlet 40″, water distribution system with nozzles 51″, fan 55″, pump60″, pipe 65″, mist eliminator 71″, air-to-water heat exchanger 230′,and energy recovery system 330.

Air-to-water heat exchanger 230′ comprises a housing 231′, heatexchanger cold water inlet 213′, and heat exchanger warm water outlet214′.

Air inlet 35″ sits near the bottom of cooling tower 310 in theembodiment depicted by FIG. 3. Other embodiments exist in which airinlet 35″ sits remotely from cooling tower 310 as long as ambient airenters cooling tower 310 below air outlet 40″. Air-to-water heatexchanger 230′ sits between air inlet 35″ and cooling tower 310.Cold-water reservoir 20″ sits near the bottom of cooling tower 310. Butother embodiments exist in which cold-water reservoir 20″ sits remotelyfrom cooling tower 310. In those types of embodiments, one of ordinaryskill in the art would recognize that additional piping and plumbingwould be useful in such embodiments. As in cooling tower 210, variousembodiments exist in which cold-water reservoir 20 and cold-waterreservoir 20′ are located remotely from cooling tower 10 and coolingtower 210, respectively.

In some embodiments, fan 55″ assists air in flowing through coolingtower 310. Fan 55″ sits on the top of cooling tower 310 near air outlet40″. Fan 55″ may sit downstream of mist eliminator 71″ or upstream ofmist eliminator 71″. Alternatively, a fan mounts at the inlet of coolingtower 310, designed to push ambient air through cooling tower 310. Ofcourse, a cooling tower may use two or more fans.

In some embodiments, water is distributed by the water distributionsystem with nozzles 51″ over a mass heat transfer media (fill). In thesetypes of embodiments, one of ordinary skill in the art would recognizethat the mass heat transfer interaction between the water and air on thesurface of the fill.

Pump 60″ is in fluid communication with cold-water reservoir 20″ and influid communication with water distribution system with nozzles 51″located near the uppermost part of cooling tower 310. In someembodiments, fluid communication encompasses a pipe 65″, connectedbetween pump 60″ and water distribution system with nozzles 51″.

In some embodiments, pump 60″ services water distribution system withnozzles 51″. In these or other embodiments, pump 60″ or another pumppumps cold water from cold-water reservoir 20″ to a cooling load (suchas cooling loads 11″ or a makeup air handling unit 715). Inventionembodiments may cool any suitable cooling load (cooling loads 11″).Suitable cooling loads can be virtually any cooling load and include thefollowing cool loads: environmental cooling (HVAC), building comfortcooling, process cooling, individual server enclosure/rack cooling, orany electronics enclosure generating a heat load. In some embodiments,the cooling load is a make up air handling unit (MU Air Handling Unit orMUAHU). In some embodiments, any cooling load that can be cooled withone or more cooling coils is suitable for this invention.

In some embodiments, such as the embodiment depicted in FIG. 8, energyrecovery systems, such as energy recovery systems (ERS) 330 comprise awater circulation system comprising a pump 860 and an air-to-water heatexchanger 830. A particulate filter 831 sits upstream of air-to-waterheat exchanger 830, between an associated cooling tower and air-to-waterheat exchanger 830. After air-to-water heat exchanger 830 comes fan 835and finally exhaust air outlet 836 to atmospheric air. ERS 330 connectsto any suitable cooling load 811 through a closed-loop water circulationsystem. The water circulation system comprises air-to-water heatexchanger 830, warm water inlet pipe 866, pump 860, cooling load 811,and cold water outlet pipe 865. Beginning with air-to-water heatexchanger 830, cold water outlet pipe 865 connects to the output ofair-to-water heat exchanger 830 and connects to the cold water inlet ofcooling load 811. The warm water outlet of cooling load 811 connects topump 860. Pump 860 connects to warm water inlet pipe 866, which in turnconnects to the warm water inlet of air-to-water heat exchanger 830. ERS330 recovers “coolness” from the cool air exhaust stream of anassociated cooling tower. Since this is a closed loop fluid circulatingsystem, the water can be any suitable heat transfer fluid including awater and glycol mixture.

In some embodiments, energy recovery system 330 operates in conjunctionwith dampers 340, 341 in an associated cooling tower. Damper 340 sits inthe air outlet pathway and damper 341 sits in the ERS air pathway. Bothare disposed to allow the air flow to be adjusted from 100% through airoutlet 40″ and 0% through ERS 330, 0% air outlet 40″ to 100% through ERS330, or any combination of air flows. Any of the cooling tower examplesdescribed in this document may additionally comprise an energy recoverysystem located at the air outlet of the cooling tower.

In any of the cooling tower types, one or more pumps may be variablespeed pumps or fixed speed pumps. In any of the cooling tower types, oneor more fans may be fixed speed fans or variable speed fans.

In addition to the components discussed above, the cooling towerscomprise monitoring and command-and-control hardware and optionallysoftware, to monitor and control the operation of the cooling towers.Various types of monitoring and command-and-control hardware andsoftware are familiar to those of ordinary skill in the art. Forinstance, variable speed fans have command-and-control hardware andsoftware that operate to vary the speed of fans to control airflowthrough the cooling towers. Variable speed pumps havecommand-and-control hardware and software to control the flow rate ofcold water from cold-water reservoir through the various othercomponents of the cooling tower and to cooling loads. Control over suchcomponents is based on the cooling needs of the cooling load, outsidetemperatures, etc. Control is exercised in some embodiments to only runnecessary fans, pumps, etc. to meet the necessary cooling load withoutwasting energy. One category of energy that is saved because of theintervening command and control systems, is energy normally wasted byoperating fans, pumps, etc. faster or at a higher capacity thannecessary to satisfy the cooling load demands on the cooling system. Insome embodiments, components of the MECS are operated by a dedicatedcontrol system communicating with a building energy management system.The control software of the control system optimizes the operation ofthe cooling system components to meet variable or constant conditionedspace cooling loads, process cooling loads, or other cooling loads atthe absolute lowest or minimum amount of energy consumption.

FIG. 4 depicts an embodiment of an invention cooling system. Coolingsystem 400 comprises three cooling towers: a Type-I cooling tower,cooling tower 401; a Type-II cooling tower, cooling tower 402; and aType-III cooling tower, cooling tower 403. Cold-water reservoir 20 ofcooling tower 401 connects through cold water outlet 65 to heatexchanger cold water inlet 213, which connects to air-to-water heatexchanger 230 of cooling tower 402. Air-to-water heat exchanger 230 ofcooling tower 402 connects through heat exchanger warm water outlet 214to warm water inlet 66, which returns warm water to cooling tower 401,as shown in the figure. In some embodiments, warm water returns to thewater distribution system with nozzles 51 of cooling tower 401.

Cold-water reservoir 20′ of cooling tower 402 connects through coldwater outlet 65′ to heat exchanger cold water inlet 213′ of air-to-waterheat exchanger 230′ of cooling tower 403. Air-to-water heat exchanger230′ connects through heat exchanger warm water outlet 214′, to warmwater inlet 66′, which returns warm water to cooling tower 402, as shownin FIG. 4. In some embodiments, warm water returns to the waterdistribution system with nozzles 51′ of cooling tower 402.

Cold-water reservoir 20″ of cooling tower 403 has cold water outlet 65″that connects to the cold water inlet of any suitable cooling load 11″.Likewise, warm-water returns through warm water inlet 66″ connecting thewarm water outlet of cooling load 11″ to the water distribution systemwith nozzles 51″ of cooling tower 403.

Cold-water reservoir 20 of cooling tower 401 and cold-water reservoir20′ of cooling tower 402 may connect to optional cold-water supply andwarm-water return lines connecting to various different cooling loads11, 11′. One of ordinary skill in the art would choose which cold-waterreservoir (which cooling stage) to use based on the nature of thecooling load. In some embodiments, the cooling system comprises four ormore cooling towers.

FIG. 5 depicts cooling system 500, which is similar to cooling system400 of FIG. 4, discussed above. In addition to the components andconnectivity discussed for the cooling system above, this cooling systemcontains at least one energy recovery system 330 wherein the energyrecovery system 330 attaches to one or more cooling towers such ascooling towers 501, 502, 503 to recapture the “coolness” of cold airexiting from the cooling tower. In some embodiments, cooling system 500comprises a second or third energy recovery system 330, 330′ on thesecond or third cooling towers, such as cooling tower 502 or coolingtower 503. And in some embodiments, the cooling system comprises four ormore cooling stages with an energy recovery system on one or morecooling towers.

One typical, suitable cooling load for a cooling system such as coolingsystem 400 or 500 is a Make Up Air Handling Unit (MUAHU).

Makeup Air Handling Unit 715 comprises one or more air particulatefilters 750 at or near air inlet 720 of MUAHU 715. Following the airpath through MUAHU 715, air-to-air heat exchanger 745 is downstream ofair inlet 720 and air particulate filters 750. Air-to-air heat exchanger745 comprises two air paths that do not mix with each other. One ofthose air paths relates to the make up air and the other relates to thebuilding exhaust air. Fan 755 pulls building exhaust air throughair-to-air heat exchanger 745, and fan 735 pulls make up air throughair-to-air heat exchanger 745. An air-to-water heat exchanger 740 comesafter air-to-air heat exchanger 745 in MUAHU 715. A variable or fixedspeed supply fan 735 is disposed in MUAHU 715 downstream of air-to-waterheat exchanger 740. In some embodiments, a high pressure water foghumidifier 732 (or other types of direct adiabatic humidifiers) isdisposed in MUAHU 715 downstream of variable or fixed speed supply fan735. In some embodiments, a mist eliminator 730 sits near air outlet 731of MUAHU 715 downstream of the humidifier 732. Cold water outlet 65″transports cold water from a cooling system to the cold water inlet ofair-to-water heat exchanger 740. Warm water inlet 66″ transports warmwater from the warm water outlet of air-to-water heat exchanger 740 backto the cooling system.

In some embodiments, components of the MECS are operated by a dedicatedcontrol system communicating with a building energy management system.The control software of the control system optimizes the operation ofthe cooling system components to meet variable or constant conditionedspace cooling loads, process cooling loads, or other cooling loads atthe absolute lowest or minimum amount of energy consumption. Executingthis software, the control system, depending on the conditioned spaceload, the process cooling load, or some other cooling load and indoorand outdoor air dry bulb and wet bulb temperatures, automaticallyprovides the necessary speed control over cooling towers fans, supplyair fans of makeup air-handling units, return and supply air fans,return and supply air humidifiers, etc., and the necessary flow controlover the cooling fluids by controlling pumps, which are typicalcomponents of commercial, industrial, or other cooling systems. Thecontrol system also automatically adjusts all operational components ofthe MECS to achieve the amount of cooling needed for the load in realtime to maximum cooling efficiency.

In some embodiments, determined by the cooling application and theenvironmental conditions of the specific geographical area, componentsof the MECS are rearranged in an order and sequence and properly sizedto maximize the generation of cold water for given environments. Thesecooling applications or any kind of cooling application in commercialreal estate buildings, industrial real estate buildings, and governmentreal estate buildings; manufacturing plants; industrial processingplants; food/beverage processing plants and agricultural buildings.

In some embodiments, an individual electronics enclosure cooling systemuses cold water generated by the different stages of the MECS to applyprocess cooling method to each cooling load in each individualelectronics enclosure. In some embodiments, invention cooling systemsare optimized for providing cold water to individual electronicenclosures or racks, such as server racks to cool the loads. Theelectronics enclosure is designed to allow space air to be drawn in tocool the electronics equipment inside the enclosure through an air inletand further pulled through the enclosure to an air outlet exit point.The warm air, which was heated by the electronics within the enclosure,exits the air outlet of the enclosure and enters into an air inlet ofone or more fan coils units. There the warm air is cooled by circulatingcooling water such as from an invention cooling system, i.e. cold waterfrom different stages of the MECS, before the cooled air is returned tothe space from the air outlet of the fan coil unit.

Cooling system embodiments exist comprising 2-10, 2-5, 5, 4, 3, or 2types of cooling towers or cooling tower cells. Each of theseembodiments comprises 0, 1, or 2 energy recovery system per coolingtower.

Operation of MECS System

Operationally, any cooling tower suitable for use with the coolingsystems of the current invention operates as described below. A coolingtower cools incoming ambient air and water from the cold-water reservoir20. Fan 55 assists in moving air through the cooling tower. Ambient airenters the cooling tower through air inlet 35 and exits the coolingtower at the top through air outlet 40. As the fan pulls air into thecooling tower, water distribution system with nozzles 51 introduceswater on top of the fill through water distribution system nozzles 51causing or allowing contact between the moving ambient air and thefalling liquid water within the fill. The cooled falling liquid water iscollected in the cold-water reservoir 20 and the saturated cold airexits the cooling tower through air outlet 40.

Pump 60 pumps water from cold-water reservoir 20 through cold wateroutlet 65 to a cooling load, such as air-to-water heat exchanger 230.After moving through the cooling load, the now warmer, cold watertravels through warm water inlet 66 into water distribution system withnozzles 51 located above the fill of cooling tower 10. Water fallingfrom the top of cooling tower 10 passes by ambient air moving from airinlet 35 at the bottom of cooling tower 10 to air outlet 40 at the topof cooling tower 10. Fan 55 moves air through cooling tower 10.

This air-water interaction causes some water to evaporate. Waterevaporation requires energy, in this case, the energy is extracted fromthe water flowing through the fill, leaving the water at a lowertemperature and the air exiting air outlet 40 at DB temperature lowerthan ambient air temperature. That is, the air-water interaction lowersthe temperature of the air as the air passes through the cooling tower.Cold water falls to the bottom of cooling tower 10 and collects incold-water reservoir 20.

All psychometric parameters of the given air have direct correlationwith each other in any kind of cooling apparatus. Knowing the dry bulbtemperature, the wet bulb temperature, and the barometric pressure ofthe air allows the determination of all other parameters of the air suchas enthalpy, relative humidity, dew point temperature, absolute moisturecontent, specific volume, etc. For a particular sample of air, themaximum wet bulb temperature is equal to the dry bulb temperature.Larger differences between the dry bulb temperature and the wet bulbtemperature indicate drier air.

One of ordinary skill in the art knows that adiabatic cooling of aparticular sample of ambient air equal to or below its wet bulbtemperature is not possible. During the adiabatic air cooling process,the air's dry bulb temperature is lowered and its moisture content isincreased, however, its wet bulb temperature and enthalpy do not change.This has ramifications in using evaporative cooling towers.

Cold-water reservoir 20 located near the bottom of cooling tower 401feeds cooling loads 11. The warm water from cooling load 11 connects towarm water inlet 66, and to water distribution system with nozzles 51 ofcooling tower 401 completing the cycle. Gravity causes the water to fallthrough the cooling tower fill back into the cold-water reservoir.During this trip, the water again interacts with the air flowing upthrough the cooling tower and is in direct contact with the air flowingthrough the cooling tower. The main result from this air-water contactis that, as before, some amount of the water evaporates in the airflowing up through the cooling tower. And the cycle continues.

The difference between the dry bulb temperature and the wet bulbtemperature is smaller after passing through the cooling tower.Therefore, one of ordinary skill in the art recognizes that the tripthrough the cooling tower lowers the temperature of the water.

Each of the multiplicity of invention cooling towers operates in thismanner. The temperature of the cold water generated by any cooling toweris dependent on the wet bulb temperature of the air entering the coolingtower. The cooling towers use ambient air during operation. Therefore,the only way of attaining cold water temperatures lower than the wetbulb temperature of the ambient air, is to lower the wet bulb and drybulb temperatures of the ambient air entering the cooling tower. Inother words, sensible pre-cooling of the ambient air entering thecooling tower reduces its wet bulb and dry bulb temperature therebyallowing colder water temperatures to be achieved at each cooling stage.

The Type-II cooling towers and Type-III cooling towers add sensiblepre-cooling of the ambient air entering the cooling towers through anair-to-water heat exchanger at their air inlets. These air-to-water heatexchangers, also called pre-cooling heat exchangers sit between theirrespective air inlet and respective cooling tower. A cold-waterreservoir of another stage of the cooling system or of a previous stageof the cooling system provides cold water for the air-to-water heatexchanger. As ambient air passes through the heat exchanger, it coolsand water from the cold-water reservoir warms. The water returns to thesource cooling tower water distribution system with nozzles 51continuing the cycle. The source cooling tower ultimately removes theheat gained by the cold water as it passed through the air-to-water heatexchanger.

The ambient air passes through the air-to-water heat exchangers whichlowers the wet bulb and dry bulb temperatures of the air entering theType-II or Type-III cooling towers. Since the wet bulb temperatureserves as the lower limit for the temperature of the cold-water in thiscooling towers and since the wet bulb temperature of the pre-cooled airis lower than that of the incoming ambient air in a previous coolingstage, the Type-II or Type-III cooling tower produces cold water with atemperature lower than cold water produced by an earlier cooling stage.This ability of a later cooling stage to produce colder water than anearlier cooling stage stems directly from the fact that the sensiblepre-cooling of ambient air without exposing it to added moisturesimultaneously drops the air's dry bulb and wet bulb temperatures.Dropping the wet bulb temperature of each stage's air entering thecooling towers lowers the temperature of the cold water produced bythese stages. Thus, cascading cooling towers allows the cooling systemto produce lower temperature cold water in each of the successivestages.

Returning to FIG. 4, the cooling system functions to produce cold waterto service cooling loads 11, 11′, 11″, and the cooling load resultingfrom MU Air Handling Unit 715. In cooling tower 401, fan 55 operates topull air ambient air through air inlet 35, through air-to-water heatexchanger 230, through the wet fill, past the water distribution systemwith nozzles 51, through the mist eliminator 71, up through the fan 55,and finally out air outlet 40. Simultaneously with air moving up throughthe cooling tower 401, pump 60 pumps cold water from cold-waterreservoir 20, through cold water outlet 65, connected to heat exchangercold water inlet water pipe 213, through air-to-water heat exchanger 230on cooling tower 402, out air-to-water heat exchanger 230, through heatexchanger warm water outlet water pipe 214 connected to warm water inlet66, and, completing the cycle, to water distribution system with nozzles51 of cooling tower 401. Water distribution system with nozzles 51distributes water evenly across the top of the fill of cooling tower401. The water falls by gravity through the fill of cooling tower 401 tocold-water reservoir 20. As cold water from cold-water reservoir 20moves through the system, it provides a source of indirect sensiblepre-cooling for air entering cooling tower 402 through air-to-water heatexchanger 230. The warmed water is returned to cooling tower 401 via thewater distribution system with nozzles 51.

Fan 55′ of cooling tower 402 operates to pull ambient air into coolingtower 402 through air inlet 35′, through air-to-water heat exchanger230, through the wet fill, past the water distribution system withnozzles 51, through the mist eliminator 71, up through fan 55′, andfinally out air outlet 40′ of cooling tower 402. Water from waterdistribution system with nozzles 51′ distributes water evenly across thetop of the fill of cooling tower 402. As the water falls by gravitythrough the fill of cooling tower 402, it interacts with the movingpre-cooled air stream that has been pre-cooled by air-to-water heatexchanger 230. The air-water interaction within cooling tower 402 causessome water to evaporate. This evaporation extracts (heat) energy out ofthe circulating water stream and transfers this energy to theinteracting air stream of cooling tower 402. The cold water obtained bythe result of the above air-water interaction is collected in cold-waterreservoir 20′. The journey of the cold water begins again as pump 60′pumps water from cold-water reservoir 20′ through cold water outlet 65′,to cold water inlet pipe 213′ into air-to-water heat exchanger 230′, outwarm water outlet pipe 214′, through warm water inlet 66′, into waterdistribution system with nozzles 51′. Since cooling tower 402 operateswith an air stream comprising air with a lower wet bulb temperature anddry bulb temperature (because of the air's trip through air-to-waterheat exchanger 230), the achievable temperature of the cold water incold water reservoir 20′ is substantially lower than the temperaturethat the cold water of cold water reservoir 20 can achieve.

As described above for tower 402, fan 55″ of cooling tower 403 operatesto pull ambient air into air inlet 35″, through air-to-water heatexchanger 230′, through the wet fill, past the water distribution systemwith nozzles 51″, through the mist eliminator 71″, up through fan 55″and finally out air outlet 40″ of cooling tower 403. Pump 60″ pumpswater from cold-water reservoir 20″, through pipe 65″, to cooling loads11″ and MU Air Handling Unit 715. The warm water from the above loads isreturned back to cooling tower 403 through pipe 66″. Pipe 66″ connectsto the water distribution system with nozzles 51″ of cooling tower 403which evenly distributes water across the top of the fill. As the waterfalls by gravity through the fill of cooling tower 403, it interactswith the moving pre-cooled air stream that has been pre-cooled byair-to-water heat exchanger 230. The air-water interaction withincooling tower 403 causes some water to evaporate. This evaporationextracts (heat) energy out of the circulating water stream and transfersthis energy to the interacting air stream of cooling tower 403. The coldwater obtained by the result of the above air-water interaction iscollected in cold-water reservoir 20″. The journey of the cold waterbegins again as pump 60″ pumps water from cold-water reservoir 20″ tocooling loads 11″ and MU Air Handling Unit.

The first cooling state, comprising cooling tower 401, produces coldwater that approaches the wet bulb temperature of the ambient air. Thiscold water services air-to-water heat exchanger 230, a pre-cooling heatexchanger, located at air inlet 35′ of cooling tower 402. Cooling tower402 composes part of cooling stage 2. Since the cooling system operatesto ultimately provide pre-cooled air to cooling tower 402, when coolingstage 2 comprising cooling tower 402 operates, it produces water that iscolder than the cold water produced by cooling stage 1. This colderwater ultimately provides cooling tower 403 with air that has an evenlower wet bulb and dry bulb temperature than previous stages allowingcooling tower 403 to produce cold water that is even colder than thecold water produced in the second cooling stage.

Each of cooling towers 402 and 403 uses pre-cooled air that has a lowerwet bulb temperature than ambient air. Using the pre-cooled air allowsthese cooling towers to reach significantly lower cold watertemperatures and exhaust air temperatures than cooling towers withoutair pre-cooling. In some embodiments, the cold exhaust air exiting thecooling towers is utilized as a source of energy by the Energy RecoverySystems to further produce useable cold water or cold air and to produceadditional energy savings as compared to traditional cooling methods.Such an embodiment is depicted in FIG. 5.

The cooling system depicted in FIG. 5 functions substantially similarlyto that of the cooling system of FIG. 4.

In addition to the cold water generated by the cooling towers, such ascooling towers 501, 502, 503, the cooling towers generate exhaust airthat is colder than ambient air and can be utilized as a significantenergy source for additional cooling loads. The exhaust air exits thecooling towers through air outlets 40, 40′, 40″. In some embodiments,dampers 340, 340′, 340″ control exhaust air flow out of the respectivecooling towers. These dampers divert the exhaust air flow from coolingtower air outlets 40, 40′, 40″. Dampers 340, 340′, 340″ can directexhaust air streams in the following optional ways. Option A—the dampersdirect 100% of the exhaust air through energy recovery systems 330,330′, and 330″. Option B—the dampers direct 100% of the exhaust airthrough air outlet 40, 40′, 40″ to the outside atmosphere bypassing theenergy recovery systems. Option C—based on cooling load demands, thedampers split the exhaust air stream in any desired ratio between energyrecovery systems 330, 330′, 330″ and exhaust air outlets 40, 40′, 40″.

As seen in FIG. 8, energy recover system 330 functions to reclaim someof the “coldness” from the cooling tower exhaust air by using internalfan 835 to move cool exhaust air past air-to-water heat exchangers 830in ERS 330. This cold source can be used to service any appropriatecooling load that one of ordinary skill in the art would considersuitable. Warm water from the cooling load enters air-to-water heatexchanger 830 through warm water inlet pipe 866 and travels throughair-to-water heat exchangers 830 where the water gives off heat to theair stream flowing out of the cooling tower. Next cold water flows fromthe cold water outlet of air-to-water heat exchangers 830 into coldwater outlet pipe 865. Cold water outlet pipe 865 carries the cold waterto the cold water inlet of cooling load 811 where the cold water picksup heat from cooling load 811 and flows through the warm water outlet ofcooling load 811, through pump 860 into warm water inlet pipe 866 tobegin the cycle again. Pump 860 drives the flow through the closed loopsystem.

To present a better understanding of the design and operationalspecifics of the MECS, demonstration of its cooling capability andperformance, and for eventual comparison with a Conventional MechanicalRefrigeration System, the following design conditions are used toprovide a comparable engineering analysis for both systems performingequal tasks:

EXAMPLES Example 1 Cooling Application

-   -   a) Cool a conditioned space with the summer design sensible        cooling load of approximately 92 tons of equivalent        refrigeration.    -   b) Project Location—Phoenix, Ariz.    -   c) The ASHRAE specified design ambient air parameters for        Phoenix Ariz. for cooling applications are 110.2° F. DB and        70° F. WB.    -   d) The ASHRAE specified design ambient air parameters for        Phoenix Ariz. for evaporation applications for 0.4% are 76.1° F.        WB and 96.4° F. MCDB (Mean Coincident dry bulb temperature).        (For reference only)    -   e) The indoor design air temperature is approximately 80° F. DB        at a comfortable 40 to 65% relative humidity range.    -   f) The preliminary estimate of required volume of makeup/supply        cooled air into the conditioned space is approximately 35,000        CFM.

These calculations are provided as illustrative example only for theexemplary system described herein. They do not limit the invention inany way and are only provided to guide the user in implementing otherequivalent implementations of the invention.

Typical MECS engineering design and component list selected forperforming the above-mentioned cooling.

The MECS is configured for this particular application, and it consistsof the following main components:

-   -   Three induced draft counter flow cooling towers or comparable        Air Washers; variable speed exhaust air fans; and variable flow        circulating water pumps; and.    -   Pre-cooling coils located at the ambient air inlets of the        cooling towers.

The components of makeup air-handling unit 715 sit in the followingsequence and following the airflow direction. Powered by a fixed orvariable speed supply fan 735, ambient air passes through the air inlet720 of makeup air-handling unit 715. Then it passes through airparticulate filter(s) 750 and air-to-air heater exchanger 745. Air flowthrough air-to-air heat exchanger 745 is assisted by fan 755. This airflow is building exhaust air, which pre-cools ambient air destined forintroduction into the building. Next, it reaches cooling coil 740. Coldwater is pumped from a cooling stage of a cooling system, through pipe65′ through the cold water inlet 213 to cooling coil 740 of makeupair-handling unit 715 and then through the cooling coil 740 to the warmwater outlet 214 to pipe 66′ back to the cooling system. As air passesover cooling coil 740, it gives off heat to the cold water causing thetemperature of the air to fall providing sensible cooling.

In applications where the space does not required 100% ambient air butstill has the same space cooling load, the air-to-air heat exchanger 745could be replaced with an air-mixing module (not shown). The air-mixingmodule mixes large volumes of lower temperature return air from theconditioned space with the minimal required volume of ambient air(ventilation air). This mixed air application will significantly reducethe total energy consumption of the MECS. (Note: If this air-mixingapplication is implemented, the need for humidification is greatlyreduced or eliminated in most cases.)

Return Air Sub-System (RA Sub-System)—the RA Sub-System containsductwork, an adiabatic humidification chamber, and return air exhaustfan. The RA Sub-System controls temperature, humidity, and air volume ofthe return air stream being fed to one side of the air-to-air heatexchanger 745 or to the air-mixing module.

The integrated MECS contains the following sequential process coolingstages:

Cooling Stage-1 (Water Cooling)

From FIG. 6, this cooling stage comprises cooling tower 601 and a waterpump 60. Cooling tower 601 generates cold water that collects in itscold-water reservoir 20. Cooling stage-1 generates cold water forpre-cooling ambient air entering into the next stage cooling towers. Thecooling coil (air-to-water heat exchanger 230) pre-cools ambient airentering into the next stage cooling tower 601′ using some of the coldwater from cooling tower 601.

Cooling Stage-2 (Water Cooling)

This cooling stage comprises a second cooling tower 601′, a water pump60′, and a cooling coil (air-to-water heat exchanger 230′). Coolingtower 601′ generates cold water that collects in its cold-waterreservoir 20′ and supplies cold water to the air-to-water heat exchanger230′ of the third cooling tower 601″.

Cooling Stage-3 (Water Cooling)

This cooling stage comprises third cooling tower 601″, a water pump 60″,and a cooling coil (air-to-water heat exchanger 230′). Cooling tower601″ generates cold water that collects in its cold-water reservoir 20″,and supplies cold water to a cooling coil (air-to-water heat exchanger740) installed in the housing of makeup air-handling unit 715 or someother cooling load or process cooling load.

Cooling Stage-4 (Makeup Air Cooling)

This cooling stage comprises a cooling coil (air-to-water heat exchanger740) installed in the makeup air-handling unit. The cooling coil(air-to-water heat exchanger 740) receives cold water from third coolingtower 601″. The cooling coil (air-to-water heat exchanger 740) sits inthe housing of makeup air-handling unit 715 downstream of an air-to-airheat exchanger 745 and can either cool air leaving the air-to-air heatexchanger 745 or, if the air-to-air heat exchanger is not included,pre-cools warm ambient air as it enters into the makeup air-handlingunit 715.

Cooling Stage-5 (Makeup Air Cooling)

This stage is the final cooling stage inside of the makeup air-handlingunit 715. It provides adiabatic cooling of the supply air using anysuitable direct evaporative cooling system 732, such as using highpressure water fogging nozzles.

Cooling Stage-6 (Return Air Cooling)

This cooling stage is a part of the return air RA Sub-System, combiningthe return air (RA) ductwork, evaporative air humidification chamber,and the RA exhaust fan. The humidification chamber comprises ahumidifier that could be either a high-pressure water dispersion type,or any other evaporative humidifier type appropriate for theapplication. The purpose of cooling stage-6 is to providehigh-efficiency adiabatic cooling of the RA stream before its heatexchange interaction with the warm ambient air stream in the air-to-airheat exchanger 745, or before mixing with ambient air (ventilation air)in the air-mixing module, if the cooling system is configured to use anair-mixing module.

Cooling Stage-7 (Makeup Air Cooling)

This cooling stage is an air-to-air heat exchanger and its function isto pre-cool outside warm air using the lower temperature return airstream from the conditioned space and thereby reduce the MECS totalenergy use.

Different cooling applications call for varying MECS configurations.

Each MECS is configured to produce the required amount of cooling for adefined application, such as conditioned space or process cooling forindustry. Each design factors in the peak cooling demand at summerconditions for the local environment.

The MECS has a dedicated control and monitoring system with appropriatesoftware to provide optimum, moment-to-moment control over operatingparameters that yield the required amount of cooling at minimal powerconsumption based on constantly changing building cooling loads, processcooling loads, and ambient air conditions.

MECS Cooling Stages—Divided into Water and Air Cooling Stages

Described in a different way, in general, all cooling stages of MECSfall into two states: a water-cooling stage and an air-cooling stage.

A. Water Cooling Stages

The three water-cooling stages of the MECS use three cooling towers601,601′,601″ with each stage having a cooling tower, a cooling coil(optional in the first cooling tower), and a pump arranged in series toprovide a cascade of cooling stages. That is, the cooling tower of apreceding stage generates cold water similarly to prior art coolingtowers. This cold water is used to pre-cool the incoming air of asucceeding stage, allowing the cooling tower of the succeeding stage toproduce cooler water than was possible in the preceding stage. In someembodiments, this cascading of one cooling tower after another with alower stage bolstering the cooling ability of a higher stage continues,giving cooling systems with 3, 4, 5, or more successive stages, eachstage capable of producing cold water at successively coldertemperatures.

MECS operation begins with a command from the central computer of theenergy management system and from the local programmable logiccontroller. The operation of the MECS takes place in the followingsequential steps:

Step-1

The fan 655 of the first cooling tower 601 starts, using a slow startmethod. Water circulating pump 60 starts, using a slow start method. Thepump 60 takes cold water from the cold-water reservoir 20 and directsthe water to pre-cooling coil (air-to-water heat exchanger 230)installed at the ambient air intakes of another cooling tower(s),respectively. Water, warmed by pre-cooling coils, returns to the sourcecooling tower and distributes the water evenly over the top of coolingtower fill, positioning it for continuing the evaporative cooling cycle.

Step-2

The fan 655′ in the second cooling tower 601′ starts, using a slow startmethod. The water circulating pump 60′ starts, using a slow startmethod. The pump 60′ takes cold water from cold-water reservoir 20′ anddirects the water to pre-cooling coil (air-to-water heat exchanger 230′)installed at the ambient air intakes of the next stage cooling tower601″. Warmed water from the pre-cooling coil returns to the sourcecooling tower 601′ and distributes the water evenly over the top of thefill of the cooling tower for continuing the evaporative cooling cycle.

Step-3

The fan 655 “of the third cooling tower 601” starts, using a slow startmethod. The water circulating pump 60″ starts, using a slow startmethod. The pump 60″ takes cold water from the cold-water reservoir 20″and directs the water to pre-cooling coil (air-to-water heat exchanger740′) installed in the makeup air-handling unit 715. The warm water fromthe pre-cooling coil returns to the source cooling tower 601′ anddistributes the water evenly over the top of the fill for continuing theevaporative cooling cycle.

Due to the heat-mass transfer process taking place in the fill of allcooling towers, part of the water falling over the cooling tower fillevaporates and this evaporation process lowers the temperature of theremaining water that is falling through the cooling tower and collectedin the cold-water reservoirs. The dry bulb temperature of ambient airentering into the pre-cooling coils is higher than the temperature ofthe cooling coil cooling water. The pre-cooling coils extract someamount of heat from the ambient air and, as a result, the dry bulb andwet bulb temperatures of the ambient air falls (is lowered). Thecalculations for the embodiment assume approach temperatures for coolingtowers 2° F., and approach temperatures for pre-cooling coils 3° F.

These approach temperatures have been selected as illustrative examplesonly for the exemplary system described herein. Other approachtemperatures may be applied that will provide a varying degree ofresults. The cooling towers may have approach temperatures that aredifferent from one another or that are the same. Pre-cooling coils mayhave approach temperatures that are different from one another or thatare the same.

Step-4

Supply fan 735 of makeup air-handling unit 715 starts, using a slowstart method.

Step-5

The RA exhaust fan of the RA Sub System starts, using the slow startmethod.

Step-6

After the cooling system achieves the desired cold air supply from themakeup air-handling unit and achieves the desired temperature for theair leaving the pre-cooling coil, the control system, based onestablished parameters, activates the humidifier 730 at its minimumcapacity and gradually adjusts its humidification capacity to humidifyair as set out in the specific design specifications of the applicationfor the conditioned space.

Step-7

After the cooling system achieves the desired cold air supply from themakeup air-handling unit 715, the control system adjusts and regulatesthe return air fan to meet the desired volume of return air.

Step-8

After the supply and return airflows are balanced as desired, thecontrol system activates the humidifier in the RA Sub System at itsminimum capacity and gradually adjusts its humidification capacity untilit optimizes the humidification level to provide the lowest possibletemperature of the return air stream. Lower air stream temperatures atthis point provide maximum pre-cooling of ambient air in the air-to-airheat exchanger.

Example 2

The following estimates show cold water temperatures leaving the coolingtowers for a cooling system design based on summer ambient airconditions for Phoenix, Ariz., and according to the MECS (coolingsystem) design. Since ASHRAE-specified design ambient air parameters forPhoenix, Ariz., for evaporation applications for 0.4% are 76.1° F. WBand 96.4° F. MCDB (evaporative application) exist at peak conditions foronly a very short cooling time, these analysis and calculations focus onthe ASHRAE Cooling Application corresponding to ambient air parametersfor Phoenix, Ariz., of 110.2° F. DB and 70.0° F. WB temperatures. Theseparameters approximate some of the least favorable conditions for usingevaporative cooling systems in Phoenix.

The estimated theoretical temperatures of cold water exiting any coolingtower with a design approach temperature of 2° F. operating at thedesign ambient air conditions of 76.1° F. WB and 96.4° F. MCDB(evaporative application) without using pre-cooling coils isapproximately 78.1° F.

The estimated theoretical temperatures of cold water exiting a similarlydesigned cooling tower operating while not using a pre-cooling coil andcooling towers operating while using pre-cooling coils at the designambient air conditions of 76.1° F. WB and 96.4° F. MCDB (evaporativeapplication) are approximately 78.1° F., 73.6° F. and 72.6° F.,respectively.

The estimated theoretical temperatures of cold water exiting any coolingtower with a design approach temperature of 2° F. (operating withoutpre-cooling coils) at the design ambient air conditions of 110° F. DBand 70° F. WB (cooling application) is approximately 72° F.

The estimated theoretical temperatures of cold water exiting a similarlydesigned cooling tower operating while not using a pre-cooling coil andsecond and third stage cooling towers operating while using pre-coolingcoils at the design ambient air conditions of 110° F. DB and 70° F. WB(cooling application) are approximately 72° F., 60.2° F. and 55.5° F.,respectively.

The design approach temperature for all the cooling towers is 2° F. Thedesign approach temperature for all cooling coils in this calculation is3° F. But approach temperatures may change to meet specific coolingdesign applications for specific locations and design parameters andwill result in varying cooling results.

It should be noted that the estimated temperature values of cold watershown above for the cooling and evaporative applications does notinclude the pre-cooling of ambient air in the cooling coil located atthe air intake of the first cooling tower. If the MECS design includesthe cooling effect of the cooling coil, the water temperatures leavingthe next stage cooling towers would be lower.

Sequential Cold Water Temperature Chain of the MECS Water Cooling Stages

The temperature of cold water exiting the third cooling tower isapproximately 55.5° F., lower than the temperature of cold water exitingthe second cooling tower, and the temperature of cold water exiting thesecond cooling tower is approximately 60.2° F., lower than thetemperature of cold water exiting the first cooling tower, which isapproximately 72° F. Another means of stating the above is that thetemperature of cold water exiting cooling towers is that the thirdcooling tower is approximately 55.5° F. which is less than the secondcooling tower of approximately 60.2° F. which is less than the firstcooling tower of approximately 72° F. In this design example, theinitial ambient air wet bulb temperature is 70° F. Therefore, in thisexample, an invention cooling system provides evaporatively cooled coldwater exiting the final cooling tower at approximately 55.5° F., whichis lower than the 70° F. initial wet bulb temperature of the ambientair.

Some invention cooling systems achieve these effects using variousmethods and systems consisting of the following:

Pre-cooling the ambient air entering into the cooling tower(s) withcooling coil(s) to provide sensible cooling of the entering air forlowering the ambient air's dry bulb and wet bulb temperatures.

If more than one cooling tower is arranged in series (cascaded) to meeta specific application, cold water from a first stage cooling tower issupplied to the cooling coil of the second cooling tower and to otheroptional cooling loads. Cold water from a second stage cooling tower issupplied to the coiling coil to a third or subsequent stage coolingtowers and to other optional cooling loads. Cold water from a second,third, or greater stage is supplied to the cooling coil in the makeupair-handling unit and may be supplied to other optional cooling loads.

For the specific local design conditions and specific coolingapplication, the piping system configuration supplying cold water orcold air to the air or water cooling loads can be modified to provideflexibility in operating any combination of cooling towers.

In all cases, invention methods of arranging the cooling towers in aseries/cascade providing for the operation of the cooling towercombinations using special direct/indirect evaporation techniques isable to generate cold water with a final temperature lower than theinitial wet bulb temperature of ambient air. The temperature of coldwater generated by MECS can be used to satisfy a majority of HVAC andprocess cooling applications while using significantly lower energy ascompared to conventional mechanical refrigeration systems.

Air Cooling Stages

The makeup air-handling unit cools the makeup air for this particularapplication. The makeup air-handling unit comprises a pre-cooling coilproviding sensible cooling (cooling stage-4) of the ambient air, anevaporative humidifier providing additional (if necessary) adiabaticcooling of the makeup air (cooling stage-5), and either an air-to-airheat exchanger (cooling stage-7) or air-mixing section or both use thereturn air from the conditioned space.

Cooling Stage-4 (Makeup Air Cooling)

The makeup air-handling unit fan pulls the required amount of the makeup(ambient) air into the makeup air-handling unit housing through the airintake louver. The air then passes through the air filter section, theair-to-air heat exchanger section, and enters into the pre-cooling coil,which cools makeup air using cold water supplied from cooling tower.(Note: At this point, it is not assumed that an air-to-air heatexchanger is incorporated thereby facilitating the next statement.) Airenters pre-cooling coil at conditions of 110.2° F. DB and 70° F. WBtemperature and leaves pre-cooling coil at approximately 58.5° F. DB and51.5° F. WB temperature. The sensible cooling load for pre-cooling coilfor a cooling application described herein is approximately 168.0 tonsof equivalent refrigeration.

Note: For demonstration of the available cooling capacity of the MECS,we do not take into consideration the heat rejected from the ambient airstream by pre-cooling the return air stream in the air-to-air heatexchanger.

Cooling Stage-5 (Makeup Air Cooling)

Cooling Stage-5 further increases cooling capacity of the cooled supplyair, reducing its dry bulb temperature by means of adiabatic cooling ofambient air coming through the pre-cooling coil. Cooling Stage-5comprises an evaporative air humidifier installed in the makeupair-handling unit housing downstream of the supply air fan. Theadiabatic cooling capacity of cooling stage-5 is approximately 96,485BTU/hr or 8 tons of equivalent refrigeration. The humidifier could beeither a high-pressure water dispersion type or any other type ofevaporative humidifier appropriate for the application. The integratedpart of the cooling stage-5 is a mist eliminator situated downstream ofthe humidifier. The parameters of the supply air leaving cooling stage 5and entering into the conditioned space are approximately 51.8° F. DBand 51.3° F. WB at the total supply airflow rate of approximately 35,000CFM (air mass flow is equivalent to 160,809 lbs/hr). Assuming acondition space temperature of 80° F. DB, the assimilating sensiblecooling capacity of the supply air is approximately 92 tons ofequivalent refrigeration.

Cooling Stage-6 (Return Air Cooling)

The air cooling stage-6 provides the high-efficiency adiabatic coolingof the RA stream to reduce its temperature as low as possible before itsheat exchange interaction with the warm ambient air stream in theair-to-air heat exchanger which is part of cooling stage-7. This aircooling stage-6 is a part of the RA Sub-System, combining the RAductwork, evaporative air humidification chamber, and the air-to-airheat exchanger physically located in the makeup air-handling unithousing. The humidification chamber comprises the humidifier, whichcould be either a high-pressure water dispersion type or any otherappropriate type of evaporative humidifier matching the application. Theintegrated part of cooling stage-6 is a mist eliminator situateddownstream of the humidifier in the humidification chamber.

Cooling Stage-7 (Makeup Air Cooling)

Cooling Stage-7 allows significant reduction in the total energy usageby the MECS, especially at peak conditions, by pre-cooling ambient airusing the lower temperature return air from the conditioned space. Inour case, the estimated temperature of the adiabatically cooled RAentering the air-to-air heat exchanger could be within approximately75-76° F. DB range while the temperature of ambient air entering theair-to-air heat exchanger is 110.2° F. DB. The anticipated heat transferefficiency of the heat exchanger with the above interacting airstreamsis approximately 70%.

Cooling Stage-7 consists of an air-to-air heat exchanger situated atambient air intake of the makeup air-handling unit, RA exhaust fan, andRA ductwork. The RA exhaust fan is installed at the strategiclocation-downstream of the air-to-air heat exchanger. This location ofthe RA exhaust fan makes the following positive energy impacts:

It increases the total amount of heat extracted from the warm ambientair stream by eliminating the fan heat going to the RA stream resultingin the production of cooler makeup air entering into pre-cooling coiland reducing the cooling load on the pre-cooling coil.

It decreases the required amount of cold water used by pre-cooling coil,and reduces the energy consumption of all the operating cooling towersand their respective water circulating pump(s).

The makeup air-handling unit of the MECS supplies into the conditionedspace approximately 35,000 CFM of cooled air at the estimated parametersof 51.8° F. DB and 51.3° F. WB. The initial design parameters of ambientair entering into the makeup air-handling unit are 110.2° F. DB and 70°F. WB temperatures. The indoor air design parameters for the conditionedspace are approximately 80° F. DB and 62.3° F. WB temperatures. Thecooling capacities of the air cooling stages of the makeup air-handlingunit are:

-   -   Air Cooling Stage-4 168 tons of equivalent refrigeration.    -   Air Cooling Stage-5 (sensible equivalent adiabatic cooling) 8        tons of equivalent refrigeration.

The total gross air cooling capacity of the makeup air-handling unit inthis example is approximately 176 tons of equivalent refrigeration. Thetotal sensible cooling load for cooling 160,809 lbs/hr of ambient airmass at initial temperatures of 110.2° F. DB and 70° F. WB to supply airtemperatures of 51.8° F. DB and 51.3° F. WB is approximately 170 tons ofequivalent refrigeration. Therefore, to cool specified amounts ofambient air from the initial design parameters to the specifiedparameters of the supply requires a net of approximately 170 tons ofequivalent refrigeration.

35,000 CFM (mass flow rate 160,809 lbs/hr) of supply air at approximateconditions of 51.8° F. DB and 51.3° F. WB temperatures can providespecified indoor air conditions of 80° F. DB and relative humidity of62.3% in the conditioned space. The corresponding net sensible coolingcapacity of the cold supply air is approximately 92 tons of equivalentrefrigeration.

Note: The design parameters of the return air exiting the conditionedspace and entering into RA Sub-System are approximately 80° F. DB and62.3° F. WB temperatures.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications can be made without departing from theembodiments of this invention in its broader aspects and, therefore, theappended claims are to encompass within their scope all such changes andmodifications as fall within the true, intended, explained, disclose,and understood scope and spirit of this invention's multitudinousembodiments and alternative descriptions.

Additionally, various embodiments have been described above. Forconvenience's sake, combinations of aspects composing inventionembodiments have been listed in such a way that one of ordinary skill inthe art may read them exclusive of each other when they are notnecessarily intended to be exclusive. But a recitation of an aspect forone embodiment is meant to disclose its use in all embodiments in whichthat aspect can be incorporated without undue experimentation. In likemanner, a recitation of an aspect as composing part of an embodiment isa tacit recognition that a supplementary embodiment exists thatspecifically excludes that aspect. All patents, test procedures, andother documents cited in this specification are fully incorporated byreference to the extent that this material is consistent with thisspecification and for all jurisdictions in which such incorporation ispermitted.

Moreover, some embodiments recite ranges. When this is done, it is meantto disclose the ranges as a range, and to disclose each and every pointwithin the range, including end points. For those embodiments thatdisclose a specific value or condition for an aspect, supplementaryembodiments exist that are otherwise identical, but that specificallyexclude the value or the conditions for the aspect.

1-20. (canceled)
 21. A system comprising: a initial-stage (IS) coolingassembly that comprises a cooling tower having: an ambient air inletwithout an associated heat exchanger, an air outlet, a cooling fluidreservoir disposed near a bottom of the IS cooling tower; and a fandedicated to the IS cooling tower, and configured to move air throughthe IS cooling tower, a final-stage (FS) cooling assembly that comprisesa cooling tower having: an air inlet, an air outlet, a cooling fluidreservoir disposed near a bottom of the FS cooling tower, a fandedicated to the FS cooling tower, and configured to move air firstthrough the FS air-inlet heat exchanger then the FS cooling tower, aheat exchanger at the air inlet of the FS cooling tower; and a variableflow cooling fluid pump that is adapted to pump cold cooling fluidthrough FS supply piping; wherein the IS cooling fluid reservoir atleast connects to one or more of the following heat exchangers: the FSair-inlet heat exchanger; and an optional mid-stage (MS) air-inlet heatexchanger; wherein warmed cooling fluid returns directly to wet media ofthe IS cooling tower and to the IS cooling fluid reservoir for reuse,wherein the FS cooling fluid reservoir connects to a primary coolingload and optionally one or more additional cooling loads and warmedcooling fluid returns directly to wet media of the FS cooling tower andreturns to the FS cooling fluid reservoir for reuse.
 22. The system ofclaim 21 further comprising at least one pump connected between the IScooling fluid reservoir and the two or more heat exchangers.
 23. Thesystem of claim 22 where in the at least one pump is a variable-speedpump.
 24. The system of claim 23 wherein at least one fan is avariable-speed fan.
 25. The system of claim 24 wherein thecomputer-based command-and-control system is configured to monitor atleast one cooling parameter.
 26. The system of claim 25 wherein thecooling parameter is air temperature and is measured at the primarycooling load.
 27. The system of claim 26 wherein the computer-basedcommand-and-control system is configured to control at least one of theIS fan or the FS fan.
 28. The system of claim 26 additionallycomprising: the MS cooling assembly that comprises a cooling towerhaving: an air inlet, an air outlet, a cooling fluid reservoir disposednear a bottom of the MS cooling tower, a fan dedicated to the MS coolingtower, and configured to move air first through the MS air-inlet heatexchanger then the MS cooling tower, a heat exchanger at the air inletof the MS cooling tower, and a cooling fluid pump that is adapted topump cold cooling fluid through MS supply piping; wherein the MS coolingfluid reservoir connects at least to one or more of the following heatexchangers: the FS air-inlet heat exchanger; and an MS air inlet heatexchanger serving the air inlet of another optional MS cooling tower;and wherein warmed cooling fluid returns directly to wet media of the MScooling tower and to the MS cooling fluid reservoir for reuse.
 29. Thesystem of claim 28 further comprising at least one variable-speed pumpconnected between the IS cooling fluid reservoir, the MS cooling fluidreservoir, or the FS cooling fluid reservoir and the primary coolingload.
 30. The system of claim 29 wherein the computer-basedcommand-and-control system adjusts a IS variable-speed fan, an MSvariable-speed fan, or a FS variable-speed fan.
 31. The system of claim30 wherein the computer-based command-and-control system is adapted toadjust fan speed in response to a monitored parameter.
 32. The system ofclaim 31 wherein the computer-based command-and-control system isadapted to adjust cooling tower pump speed in response to the monitoredparameter.
 33. The system of claim 30 wherein the computer-basedcommand-and-control system runs software that monitors coolingparameters and optimizes cooling by modifying cooling controls.
 34. Thesystem of claim 33 wherein the computer-based command and control systemis a programmable logic controller.
 35. The system of claim 33 whereinthe IS cooling fluid reservoir additionally connects to a heat exchangerserving a cooling load other than the MS or FS air-inlet heatexchangers.
 36. The system of claim 33 wherein the MS cooling fluidreservoir additionally connects to a heat exchanger serving a coolingload other than the MS or FS air-inlet heat exchangers; or the FScooling fluid reservoir additionally connects to a heat exchangerserving a cooling load other than the primary cooling load.
 37. Thesystem of claim 33 wherein the IS cooling tower, the MS cooling tower,or the FS cooling tower further comprises an energy recovery systemconnected to the cooling tower air outlets.
 38. The system of claim 37wherein the primary cooling load is a comfort cooling load or a processcooling load.
 39. The system of claim 21 wherein the primary coolingload is a comfort cooling load or a process cooling load.
 40. The systemof claim 21 wherein the IS cooling tower or the FS cooling tower isselected from cross-flow or counter-flow cooling towers.